This invention relates to carbon black production. In one of its aspects this invention relates to apparatus for carbon black production. In another of its aspects this invention relates to the use of vortex flow in carbon black reactors. In still another aspect of the invention it relates to affecting the total angular momentum rate of the flowing mass in a carbon black reactor. In yet another aspect of the invention it relates to affecting the deposition of ash in a carbon black reactor.
In well known processes for the production of carbon black such as that disclosed in U.S. Pat. No. 2,564,700, hot combustion gases are charged to an oil furnace carbon black reactor in a tangential manner to form a vortex-flow of hot combustion gases within the combustion or precombustion zone of a carbon black reactor. Feedstock is injected axially into this vortex of hot combustion gases with axial air flow added around the feedstock injection means as a cooling medium to protect the feedstock injection means from excessive heat from the hot combustion gases. The carbon black formation reaction occurs, the reaction mass is quenched to stop further reactions, and the produced carbon black is recovered for use in such products as rubber compounds for tires and the like.
It has now been found that by affecting the angular momentum rate of the combustion gas vortex that the operation of the carbon black reactor can be greatly affected. The angular momentum rate of the mass in the reactor is affected by causing a vortex to be formed of either the feedstock, the cooling air, or both. Depending on whether the rotation of the vortex of these materials, created internally to the vortex of the hot combustion gases, is oriented in the same rotation as the combustion gases or in a counter-rotation to the combustion gases there is a respective increase in the total angular momentum rate of the mass in the reactor or a decrease in the total angular momentum rate of the mass in the reactor. Either of these conditions can have a profound effect on the operation of the carbon black reactor.
For instance, it has been found that the tangential flow of combustion gases can cause rapid ash deposition on the ceramic walls of a reacting unit when high ash-containing feed oils are used. This deposition cannot be tolerated because it results in the sloughing of the ceramic with inorganic material being carried into the carbon black product thereby increasing the "grit" content of the product. It also results in a rapid deterioration of the reactor configuration. A discussion of the slagging of ceramics or refractories used to line carbon black reactors caused by inorganic material such as cracking catalysts, sand, and the like is discussed in U.S. Pat. No. 2,794,710.
It has been found that by decreasing the strong centrifugal force developed within the combustion and precombustion chambers of a carbon black reactor without decreasing the flow of the combustion gases, i.e., maintaining the same quantity of air-fuel flow to produce the same quantity of hot combustion gases thereby producing with the same oil feed rate the same carbon black particle sizes, that deposition of ash can be minimized. This is particularly important in the production of small particle carbon black in which process the tangentially introduced hot combustion gases have very high vortex strength. By the use of the method and apparatus of the present invention the effect of the vortex flow of hot combustion gases can be decreased thereby minimizing the deposition of ash materials in the feedstock onto the lining of the reactor.
In operational carbon black reactors in which a vortex of hot combustion gases is used and in which grit is not a problem the feedstock and/or cooling air can be given the same rotational flow as that of the hot combustion gases thereby increasing the total angular momentum rate of the mass in the reactor. This increased vortex strength can, in many operations, decrease the structure of the carbon black produced.
It is therefore an object of this invention to provide method and apparatus for affecting the angular momentum rate of the mass in the reactor. It is another object of this invention to provide method and apparatus for reducing the high vortex strength of tangentially introduced hot combustion gases in a carbon black reactor. It is another object of this invention to provide method and apparatus for reducing slagging problems in carbon black production operations wherein feedstocks containing solid contaminants are used. It is another object of this invention to provide method and apparatus for increasing the vortex strength of tangential combustion gases in the production of carbon black. It is still another object of this invention to provide a method and apparatus for producing carbon black of decreased structure.
Other aspects, objects, and the various advantages of this invention will become apparent upon studying this specification, the drawings, and the appended claims.